The invention relates to electrical contact strips for use with plug-in components and solderless connectors and, more particularly, to a contact spring construction intended for mounting in a strip housing having a contact spring part and a connection part.
Spring strip housings are known to be made of insulated material and equipped with contact springs. The housings are fixed to the transverse component of a plug-in rack, so that when a plug-in unit is connected, contact blades or pins secured to the end of the plug-in unit penetrate between the contact springs and thus establish an electrical connection between the rack wiring and the electrical devices arranged in the plug-in unit. Solderless connections are increasingly being used for connections with such contact springs and strip housings.
One known contact spring construction is disclosed in U.S. Pat. No. 3,990,768. There, a base end of the contact spring is spot welded to a connection pin part adjacent a right-angle bent portion thereof. This bent portion of the connection pin is pinched in a recess between upper and lower housing parts of the contact spring strip or strip housing. By this structure, the connection pin parts of the contact springs are safely fixed in the strip housing not by means of the contact springs but substantially independently of the latter. Mechanical forces on the connection pins, such as torsion stresses which particularly occur when the connection part is employed as a wrap stem, are transmitted directly to the housing and absorbed thereby rather than by the contact springs.
However, when the sections of the connection pin parts projecting from the strip housing are employed as contact blades which are intended to be pressed into the grid bores of a printed circuit board, then the right-angle bent portion of the connection pin fixed in the housing is less suited for intercepting or transmitting the forces occurring during impression. An object of the present invention is to provide a contact spring formed with a contact spring part and a connection pin part in such a manner that the mechanical forces occurring during impression of the connection parts projecting from the strip housing into grid bores on a printed circuit board are consistently transferred to the strip housing without the contact spring part of the contact spring being negatively affected.